Bizarrely Poor Code from Bizarre Machine-Generated C Sources

[Andrew Haley]

Barak A. Pearlmutter writes:
 > Success!
 > 
 > Some working magic seems to be this:
 > 
 >     gcc -s -o particle1 \
 > 	-O3 \
 > 	-march=k8 \
 > 	-mfpmath=sse \
 > 	-finline-limit=100000 \
 > 	--param large-function-insns=1000000 \
 > 	--param inline-unit-growth=1000000 \
 > 	--param sra-field-structure-ratio=0 \
 > 	particle1.c -lm
 > 
 > although it looks like -Os gives an additional improvement.
 > 
 > This (with GCC 4.1) reduces code volume to about 16k from a previous
 > near 1M, and reduces runtime by a factor of about 2700, as compared to
 > just -O3.
 > 
 > Further improvements welcome.
 > 
 > I'd also suggest adding a section to the GCC documentation on "how to
 > use GCC as a back-end to another compiler" which gives some typical
 > magic options like the above that would be useful in circumstances
 > like these.

http://gcc.gnu.org/wiki

Enjoy...

Andrew.